ICD-10-CM 2027
ICD-10 code for radon exposure
Contact with and (suspected) exposure to radon and other naturally occurring radiation
From the official ICD-10-CM alphabetic index entry “Exposure (to) › radon”. Page updated September 29, 2026.
About coding radon exposure
The ICD-10-CM code for radon exposure is Z77.123 (Contact with and (suspected) exposure to radon and other naturally occurring radiation).
Within Z77.12, choose Z77.123 (radon and other naturally occurring radiation) only when documentation doesn't support a more specific option: mold (toxic) (Z77.120), harmful algae and algae toxins (Z77.121), noise (Z77.122) and other hazards in the physical environment (Z77.128).
The conditions in its Excludes2 note aren't part of Z77.123, but may be coded alongside it if the patient has both: radiation exposure as the cause of a confirmed condition (W88-W90, X39.0-) and radiation sickness NOS (T66).
It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.
Common questions about radon exposure ICD-10 codes
What is the ICD-10 code for radon exposure?
- Z77.123 — Contact with and (suspected) exposure to radon and other naturally occurring radiation.
Is Z77.123 billable?
- Yes. Z77.123 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Z77.123 be used as a principal diagnosis?
- No. It is not acceptable as the principal diagnosis for an inpatient stay; it may be reported as a secondary diagnosis.
Is Z77.123 a CC or MCC?
- No. Z77.123 is neither a CC nor an MCC under MS-DRG v44.0.